Yes 30-11 is too easy of a gear for intervals. I can generally do intervals up to 360W with my 34 - 10/45 at a 2% decline, otherwise I spin out. I make sure I am picky when doing harder efforts like V02max, so I will pick hills to repeat. Otherwise for Z2 (around 210-220W i think my mtb gearing is perfect
Thank you everyone for the replies.
I am very lucky to have an extensive trail network a block from my house and live where I can ride year round. This means I am on the trails more than not, though about once a week I try to hit the local bike path for some Z2 endurance riding. A friend suggested I should get a road bike (gavel, etc) if I want to maximize my training.
I appreciate all the inputā¦ I too have felt that training is training (on the MTB it is just slower). I do have access to gravel & hills for workouts, which I have been doing. Also have experienced the āspin outā and living in the 10t gear as I push the flats on endurance rides. Which has made me think maybe there is a need for a bit moreā¦ I think the bigger issue now is how to convivence the wife, that with three MTBs in the garage, I need another bike 
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Indeed. On mountain bikes this is the only gear jump that I dislike.
In my experience, the difference is bigger, because aero drag is much larger on a mountain bike than on a road bike. Thatās in addition to the added rolling resistance.
I donāt find that to be hugely problematic for e. g. endurance rides and the like.
Out of curiosity, do you do your intervals on fire roads? I cannot imagine doing intervals on trails, where I need to navigate terrain and put in power as the terrain demands.
I have a 34:11 = 31:10 as my tallest gear and I spin out at 42ā46 km/h depending on the terrain. Even 30:11 (the gear the bike came with) was perfectly adequate for Z2 riding. For a mountain bike, thatās plenty, I think.
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My hardtail MTB sees more road riding than mountain biking so Iād definitely say you donāt need a roadie. Iām not racing road on it obviously but to train on itās perfectly fine.
That being said I want a roadie now to do some racing.
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Iām a MTBer and got a gravel bike last year for racing, fast group rides and training. I have road tires for when Iām on road. For what itās worth, I put on about 2 times as much time on the gravel bike. For training, Iāve found that Iām much more diligent with that bike about picking smooth roads or gradual gravel roads for my workouts, which gives me much better consistency on power output. In the past, with mtb Iād mix my workout to get to the downhill I wantedā¦ nothing wrong with a little fun but my power was all over the place when trying to clean and climb rougher roads. I still work that into my training occasionally. I enjoy long Z2 rides (mix of road and gravel), and gravel races. Fast group rides would be out of my league on a mtb. All this makes me a better off road biker IMHO. Lastly, I run road pedals on the gravel bike, and love the feeling of the great power transfer when strictly training.
Do I need it? No, but Iāve regretted some bike purchases, and that bike is not one of themā¦
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No - Intervals on road to the trails. Ofcourse it depends how lucky you are with roads in your area to find somewhere suitable and close to trails. Where I live there is plenty of quiet roads and mtb trails everywhere 
Yes - but speed isnāt important when doing workouts, infact slowing down is probably more beneficial in terms of safety. I remember doing SS workouts at 40kmh on flat roads , since you go faster, cover more ground and more varied terrain, itās likely you will need to coast and stop more because of hazards/lights/tight turns/traffic. I find this less of a problem on mtb. the only downside is that if you run a 10-51 casette, you will need to vary your cadence dramatically, but this is good training and good specificity to MTB.
It depends on your fitness and terrain ofcourse. my 34-10 I would say anything 48km+ would be considered spining out and I was unable to keep target power. but this is rare and I plan my routes around not having the intervals in the downhills.
Ofcourse, its dependant on roads available to the user and his fitness. For me a 34t and 10-45t is perfect for on and offroad for my uses. Sure I sometimes spin a 100cadence to meet the power target but its honestly made me a much better rider, nowadays I plan around it and i rarely spin out
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My thought process is if you want stay fast or get faster is to ride your mtb as much as you can. I know it can be hard to incorporate training into with it but what I have noticed is the people I race against are on their xc bikes all the time. Good way to stay on āitā for skills and being comfortable. I think both can help, but my thought is train on what you race.
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Need ā¦ hmmmm.
Be very very careful.
Three years ago I had two XC rigs, a fatbike, and a fixed townie.
Two years ago I picked up a road bike for the trainer. Then I rode it on the road and loved the efficiency and feeling of having wings so I sold one of the XC rigs, and rode the road bike more.
I didnāt touch the fatbike for a whole winter so I sold it this spring.
Then I put 35 mm tires on the road bike and started riding everything with it and the remaining XC rig was just sitting there so I traded it for a gravel bike.
Had you told me that after 25 years thereād be no mountain bike in my quiver and that Iād be setting PBs riding drop bars Iād have snorted in my beer. Is that a risk youāre ready to take ā¦ 
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I went from doing triathlons with a road bike to a nice TT bike. Then mover over to mostly gravel a few years ago. Now sold my road and TT bikes and added a full suspension mountain bike. Not sure I could ride āeverywhereā on my gravel bike. Tried some singletrack with it but a bit too harsh a ride.
Coach @Jonathan exclusively trains outside on a mtb. If your terrain provides a steady grade for predictable output, keep sending it on the mtbš¤
āExclusivelyā is not the right wording. He sure does plenty of outside workouts on his MTB, but he also mixes in TR workouts on rollers as evidenced by his Strava profile.
It likely varies with the time of year, his personal schedule and event goals, but he does a mix of training as needed.
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If you can show me a rider or two doing back to back 20-30h weeks of base training, I will stand corrected.
I donāt understand you point?
20-30hr on an MTB base training is the same as 20-30hr base training on a road bike (you just wont go as far).
The question was do you need a road bike. My reply was no, but then itās perosnal choice.
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Not in my experience. I have a road bike that lives on the trainer and at one point, I didnāt take it off for two years. I can get my outdoor fix at least a few times/week riding outside on the mountain bike and do my training rides on the trainer.
I got hit by a car a few years ago and since then, I have had little desire to ride on the road anymore.
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The point is: While itās totally possible to ride a MTB for many hours for training, you just donāt see ppl doing huge blocks of volume on one. For a reason.
The road bike Iāve always kept around that turned into a gravel bike last year has been most helpful just as just a second bike. Only having the one mtb meant a huge amount of time and distance on all those components. Having a road/gravel bike to take some of the slack is nice and I can actually take my mtb out of commission for a few days for a proper fix while not missing the training days.
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Lol - Alex wild or Keeganā¦ they do plenty of road rides on their mtbās and average 20+ mph and loads of 20+ hour weeks. They only have started recently to train on their gravel bikes with the life time grand prix. But I still see Alex doing loads of road rides on his MTB.
Also why 20 to 30 hours? Thats a very dramatic example, most of us train closer to 10 hours. Doing a 4 hour z2 ride on your MTB makes no difference what so ever to your fitness compared to doing a 4 hour z2 ride on your road bike. Arguably its better you train on the bike you race with anyway.
I sold my road bike after didicating myself fully to XC. I have never been so fit in my life as all the extra volume cycling to trails or to areas that are suitable for outdoor TR workouts.
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Even with just these and tyres with a low profile tread itās possible to keep a realtively high average speed up.
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I do need a road bike. Just to remind me how fun the MTB actually is. When I make a ride on my road bike I miss my MTB. So that keeps the road bike in the shed again for weeks. 
Seriously though. I have a road bike on my trainer to do the TR rides. In the weekends I take my MTB for a long outside ride of about 5 hours. Sometimes itās mostly forrest or back roads (more gravel), sometimes itās paved roads for about half the time. I try to ride about 80 to 100km in that ride.
Sometimes I like to get on the road bike and do a long ride. For me having a road bike for road use just means a possible variation to my routine. Do I need it, no.
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I thought everyone here knew we need ALL the bikes.
Ok, maybe not a bmx.
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